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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        // 简单数据类型 BigInt()
        // 构造函数 ,代码可读性
        const wes = new Symbol ('Wes');
        const person = Symbol('Wes');
        console.log(wes===person);
        // false
        const classRoom = {
            [Symbol('Mark')]:{ grade: 50, gender: 'male'},
            [Symbol('oliva')]:{ grade: 80, gender: 'female'},
            [Symbol('oliva')]:{ grade: 85, gender: 'female'},
            "dl":["苗苗","探花"]
        }

        console.log(classRoom);

        for (const person in classRoom){
            // for key in 
            // symbol key 不可以被枚举
            console.log(person,'///')

        }
        const syms = Object.getOwnPropertySymbols(classRoom);
        console.log(syms);
        const data = syms.map(sym => classRoom[sym]);
        console.log(data);
    </script>
</body>
</html>